POS1236 TREATMENT TRAJECTORIES IN IDIOPATHIC INFLAMMATORY MYOPATHIES
Authors: K. Wipfler, U. Sbarigia, F. Zazzetti, A. Sheahan, I. Lin, E. Alemao, K. Michaud
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Idiopathic inflammatory myopathies (IIM) are a group of rare, heterogeneous diseases in which the hallmark feature is chronic inflammation of skeletal muscle leading to muscle weakness. Initial conventional therapy is based on expert opinion and includes glucocorticoids in combination with methotrexate, azathioprine, or mycophenolate. If this therapy is not sufficiently effective, second line therapy (calcineurin inhibitors or IVIG) may be considered. If still insufficient, escalation to rituximab or cyclophosphamide is considered. Agents not included in conventional recommended therapies have also been used and are being studied in the management of IIM. <h3>Objectives</h3> To characterize real-world treatment trajectories among individuals with IIM. <h3>Methods</h3> Data were provided by adults with IIM enrolled in FORWARD, The National Databank for Rheumatic Diseases. Participants with a co-occurring RA, SLE, or SSc diagnosis were excluded. Participant characteristics were assessed at baseline (study entry) by treatment category and significance was assessed by one way ANOVA and Fisher's exact tests, as appropriate (p&lt;0.05). Treatment category (none, steroid alone, first line without steroid, first line, second line, third line, and other DMARD) was assessed at baseline and for ultimate line of treatment reported during observation. First, second, and third line treatments were considered "conventional" and others were considered "nonconventional." <h3>Results</h3> A total of 126 participants met inclusion criteria. At baseline, 43% of participants were on first line therapy. Most of the remaining participants were either on a corticosteroid alone (23%) or were on first line therapy but without a corticosteroid (17%). A relatively small number of participants (2%) were on second line therapy, and none were on third line therapy at baseline. About 9% reported use of a nonconventional DMARD, and the remaining 6% reported no treatment. Those who reported no therapy were more likely to be male and had higher global severity scores. Across 504 person-years of observation, 47% reported first line treatment, 10% reported second line, and 3% reported third line as the most advanced conventional therapy received. The remaining 40% reported either nonconventional or no treatment. <h3>Conclusion</h3> Despite published recommendations to combine glucocorticoids with another immunosuppressive drug as part of first line therapy for IIM, many individuals with IIM are not prescribed concomitant DMARDs. In this cohort, there were no significant differences in IIM subtype, disease duration, or calendar year by conventional vs nonconventional therapy at study entry. A relatively small number of individuals with IIM reported receiving no treatment during observation, which may be due to significantly shorter follow up time in that subgroup. Future work should examine treatment response and changes in disease activity with changing lines of treatment. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Kristin Wipfler: None declared, Urbano Sbarigia Shareholder of: Johnson &amp; Johnson, Employee of: Janssen, Federico Zazzetti Shareholder of: Johnson &amp; Johnson, Employee of: Janssen, Anna Sheahan Employee of: Janssen, Iris Lin Shareholder of: Johnson &amp; Johnson, Employee of: Janssen, Evo Alemao Shareholder of: Johnson &amp; Johnson, Employee of: Janssen, Kaleb Michaud: None declared.